This invention relates generally to a method and a system for displaying target vehicle position information, and more specifically to a method and a system for displaying vehicle position based on the fusion of data from a plurality of sensor sources.
Current air traffic display systems display position report and vehicle track information based on information from a single surveillance sensor. In present systems radar sensors are the primary and often the sole means of surveillance for air traffic managers. Other sensors play only a secondary role. Typically ground control radar is used by the air traffic manager to provide a two dimensional analog display on a screen. The location of an aircraft detected by the ground control radar is indicated by a dot on the screen and is tagged with data from secondary sources. The tag information is a textual display providing the air traffic manager with information such as target identification, last assigned altitude, current altitude trend, and the like. The secondary source providing such information can be, for example, a transponder on the target aircraft.
Although multiple surveillance sensors are available, current air traffic display systems do not make use of the information available from such sensors except to provide tag information. The primary source of information used by air traffic managers has been ground control radar. Like all surveillance sensors, the surveillance data provided by ground control radar has errors inherent in the data in both the range and azimuth of the detected target aircraft. These errors occur, at least in part, because of the scanning nature of the radar.
The job of the air traffic managers is to insure a safe margin of aircraft separation while controlling an orderly and efficient pattern of takeoffs and landings. The difficulty of this job is increased by the uncertainty in aircraft position data provided by the surveillance sensors and displayed on the screen. Additionally, primary reliance on a single source of position data subjects the air traffic control system to the danger of total interruption of service if the data stream from that single source is interrupted for any reason. A need therefore exists for an improved air traffic display system and for a method for displaying target vehicle position information that will have improved accuracy and that will provide redundancy in the event that information from the primary surveillance sensor is interrupted.
In accordance with one embodiment of the invention, a method is provided for displaying target vehicle position information based on inputs from a plurality of sensors. Each of the sensors contributes traffic information data for each of the target vehicles within the range of the sensors. For each of the target vehicles, the traffic information from each of the plurality of sensors is fused to calculate a derived target position. It is this derived target position that is then displayed on the traffic display system screen. In accordance with a further embodiment of the invention, the fused data is further used to calculate a historical track of a target vehicle and a projected track for that vehicle. Preferably both the target position and the projected track are displayed with a boundary of certainty so that one using the displayed information will be aware of the uncertainty in the information.